An endotracheal tube may be inserted into the trachea of a patient who is in acute respiratory failure or is undergoing general anesthesia and requires artificial ventilation. The most common method of providing artificial ventilation is by pumping compressed air into the patient's lungs through the endotracheal tube. This tube is inserted through the patient's mouth or nose and passed between the vocal cords into the trachea. Alternatively, a tube may be inserted into the trachea through a tracheotomy surgical incision. The endotracheal tube must be placed quickly and accurately and positioned with its tip in the mid portion of the patient's trachea to prevent accidental slipping and to provide proper seal and ventilation of both lungs.
Once the endotracheal tube is in place it is secured to prevent inadvertent movement thereof during use to prevent accidents. The endotracheal tube may be secured by inflating a cuff that surrounds the tube near its distal tip. The inflated cuff occludes the space between the outer wall of the tube and the inner wall of the trachea to provide an airtight seal and hold the tube in place. Accidental insertion of the tube into the esophagus or placing it too deep inside the airways, so that its tip is lodged in one of the main stem bronchi instead of in the trachea, may lead to catastrophic consequences and asphyxiation of the patient.
For oral intubation an operator may use a laryngoscope, which consists of a handle and a blade. The operator inserts the blade into the patient's mouth and advances it until its tip lies in the pharynx beyond the root of the tongue. The handle is then used to manipulate the blade and push the tongue out of the way until the epiglottis and the vocal folds can be seen. The tip of the endotracheal tube can then be aimed and pushed between the vocal folds into the trachea. This method of insertion is used in the majority of intubations, but requires skill, training, and experience and is only performed by specialized physicians and licensed paramedics.
An alternative method that is often used requires a fiber optic bronchoscope. First the bronchoscope is connected to a light source to provide the needed illumination of the field facing its tip. The shaft of the bronchoscope is then inserted through the endotracheal tube and moved in as far as possible. The tip of bronchoscope is then inserted into the patient's airway and advanced under visualization, through the bronchoscope's eyepiece or a video display, in between the vocal folds into the trachea. The endotracheal tube can now be pushed down the bronchoscope's shaft and moved between the vocal folds into the trachea. The endotracheal tube can now be secured and the bronchoscope removed to free up the lumen of the endotracheal tube. While the bronchoscopic method is safer than intubation with the laryngoscope, the equipment needed is expensive, delicate, more cumbersome, and is seldom found in the field or on emergency medical vehicles.
Other methods to verify the placement of the endotracheal tube include: auscultation of both sides of the chest to verify symmetric air entry into both lungs, a chest x-ray to verify the tube placement but requiring further x-rays whenever the tube is placed or repositioned, a suction bulb, or through sending and receiving an acoustic signal.
Alternatively, a laryngeal mask airway (LMA) is used as a conduit for endotracheal tube placement. The laryngeal mask airway or laryngoscope mask is useful for establishing airways in unconscious patients. An example of an LMA is disclosed in U.S. Pat. No. 4,509,514, which is hereby incorporated by reference as if fully set forth herein. The LMA typically comprises a curved or flexible tube opening at a distal end into the interior of a hollow mask portion shaped to conform to and to fit readily into the actual and potential space behind the larynx and to seal around the circumference of the laryngeal inlet without penetrating into the interior of the larynx. The mask portion of the device may have an inflatable periphery or cuff which is adapted to form the seal around the laryngeal inlet. Alternatively or in addition, the mask portion may have an inflatable posterior part which is adapted to press against the back of the throat and thereby increase the sealing pressure around the laryngeal inlet.
Combining the use of the LMA and the endotracheal tube is advantageous as the LMA can provide initial ventilation of the patient and the endotracheal tube can be inserted at a later stage such as when the patient's oxygen level has reached a desired point. When an LMA is already in position, the endotracheal tube is fed through the LMA and the vocal folds into the trachea. Correct insertion and placement of the endotracheal tube by current methods remains cumbersome and problematic. The most common method—using a fiber optic bronchoscope as described above—is made more complex by the presence of the LMA.
There is an unmet need for, and it would be highly useful to have, a method and system that allowed for use of an LMA along with an endotracheal tube that allowed for simplified insertion and correct placement of the endotracheal tube and, optionally, removal of the LMA once the endotracheal tube was in place.